Strain sensors

Abstract

A strain sensor can include a resistor, a first electrical contact at a first end of the resistor, and a second electrical contact at a second end of the resistor. The resistor can be formed of a matrix of sintered elemental transition metal particles interlocked with a matrix of fused thermoplastic polymer particles.

What is claimed is: 
     
       1. A strain sensor, comprising:
 a resistor formed of a matrix of sintered elemental transition metal particles interlocked with a matrix of fused thermoplastic polymer particles, wherein the thermoplastic polymer particles comprise nylon 6 powder, nylon 9 powder, nylon 11 powder, nylon 12 powder, nylon 66 powder, nylon 612 powder, polyethylene powder, thermoplastic polyurethane powder, polypropylene powder, polyester powder, polycarbonate powder, polyether ketone powder, polyacrylate powder, polystyrene powder, or a mixture thereof; 
 a first electrical contact at a first end of the resistor; and 
 a second electrical contact at a second end of the resistor. 
 
     
     
       2. The strain sensor of  claim 1 , wherein the elemental transition metal particles comprise silver particles, copper particles, gold particles, or combinations thereof. 
     
     
       3. The strain sensor of  claim 1 , wherein the matrix of fused thermoplastic polymer particles comprises a fusing agent selected from carbon black, a near-infrared absorbing dye, a near-infrared absorbing pigment, a tungsten bronze, a molybdenum bronze, metal nanoparticles, a conjugated polymer, or combinations thereof. 
     
     
       4. The strain sensor of  claim 1 , wherein the resistor further comprises a halogen salt in the matrix of sintered elemental transition metal particles, the matrix of fused thermoplastic polymer particles, or both. 
     
     
       5. The strain sensor of  claim 1 , wherein the resistor has a resistance from 1 ohm to 1 Mega ohm. 
     
     
       6. A 3-dimensional printed part having an integrated strain sensor, comprising:
 a part body; and 
 a resistor, wherein the resistor and the part body are formed of a continuous matrix of fused thermoplastic polymer particles, wherein the resistor comprises a conductive composite of sintered elemental transition metal particles interlocked with the matrix of fused thermoplastic polymer particles in a first region, and wherein the part body is a second region of the matrix of fused thermoplastic polymer particles where the conductive composite is not present. 
 
     
     
       7. The 3-dimensional printed part of  claim 6 , wherein the elemental transition metal particles comprise silver particles, copper particles, gold particles, or combinations thereof. 
     
     
       8. The 3-dimensional printed part of  claim 6 , wherein the fused thermoplastic polymer particles comprise a fusing agent selected from carbon black, a near-infrared absorbing dye, a near-infrared absorbing pigment, a tungsten bronze, a molybdenum bronze, metal nanoparticles, a conjugated polymer, or combinations thereof. 
     
     
       9. The 3-dimensional printed part of  claim 6 , wherein the resistor further comprises a halogen salt in the matrix of sintered elemental transition metal particles, the matrix of fused thermoplastic polymer particles, or both. 
     
     
       10. The 3-dimensional printed part of  claim 6 , wherein the resistor has a resistance from 1 ohm to 1 Mega ohm. 
     
     
       11. The 3-dimensional printed part of  claim 6 , wherein the resistor is embedded in the part body. 
     
     
       12. The 3-dimensional printed part of  claim 6 , wherein the part is formed of multiple layers of fused thermoplastic polymer particles stacked in a z-axis direction, and wherein the resistor is oriented at least partially in the z-axis direction. 
     
     
       13. The 3-dimensional printed part of  claim 6 , wherein the thermoplastic polymer particles comprise nylon 6 powder, nylon 9 powder, nylon 11 powder, nylon 12 powder, nylon 66 powder, nylon 612 powder, polyethylene powder, thermoplastic polyurethane powder, polypropylene powder, polyester powder, polycarbonate powder, polyether ketone powder, polyacrylate powder, polystyrene powder, or a mixture thereof. 
     
     
       14. A method of making a 3-dimensional printed part having an integrated strain sensor in accordance with the strain sensor of  claim 1 , the method comprising:
 dispensing a conductive fusing ink onto a first area of a layer of thermoplastic polymer particles, wherein the conductive fusing ink comprises a transition metal; 
 dispensing a second fusing ink onto a second area of the layer of thermoplastic polymer particles, wherein the second fusing ink comprises a fusing agent capable of absorbing electromagnetic radiation to produce heat; and 
 fusing the first and second areas with electromagnetic radiation to form the resistor in the first area and a part body in the second area comprising the fused thermoplastic polymer particles. 
 
     
     
       15. The method of  claim 14 , wherein the resistor is formed at least partially oriented in a z-axis direction such that the resistor extends across multiple layers of the 3-dimensional printed part. 
     
     
       16. The method of  claim 14 , wherein the transition metal is in the form of elemental transition metal particles.